(1) Field of the Invention
The present invention relates to a printing apparatus for printing image data obtained by a digital camera or the like, and the printing method.
(2) Description of the Related Art
When a home printer prints the image data obtained by a digital camera, a user conventionally transmits the image data to a personal computer (PC). The user then selects the image to be printed and performs graphic processing on the selected image by using an application installed in the PC, transmits the image data from the PC to the printer and has the printer print it.
Recently, however, with the spread of digital cameras, systems have been conceived with the view to facilitate printing. One of the examples is a system in which a digital camera and a printer are connected directly without PC, the image data obtained by the digital camera is transmitted directly to the printer, and the printer prints the image data. Under such system, generally referred to as a “direct-printing system”, a liquid-crystal-display screen for displaying the images to be printed is loaded on the digital camera or on the printer so that the user can select easily the images for printing. A method of creating an index print, in which plural thumbnail images are arranged in an array as shown in FIG. 1, is employed as well by the printer. In this case, the user selects the image to be printed while looking at the index print. It should be noted that FIG. 1 shows an example of print data for the images in the index print. Most of the image data obtained by the digital camera is a file in an Exchangeable Image File (Exif) format which includes, in a single file, the image data of main images and that of thumbnail images having a resolution lower than that of main images. The printer obtains only the image data of thumbnail images included in the Exif file, when creating an index print. The data amount of thumbnail images is smaller than that of main images. It is therefore possible to shorten the time required for creating the index print in the case where the printer obtains only the image data of thumbnail images (see reference to, for example, Japanese Open-Laid Patent Application No. 2001-197406 for an exclusive obtainment of the image data of thumbnail images).
Meanwhile, another way of handling easily the images based on the image data obtained by the digital camera is to display the images on a TV screen at home. For example, some digital TVs of the latest technology are equipped with a memory-card slot. When a memory card, on which the image data obtained by the digital camera is stored, is inserted into the memory-card slot, the digital TV reads out the image data stored in the memory card and displays on the display the images based on the image data.
An application for processing the image data obtained by the digital camera is installed in an AV (Audio-Visual) device such as the digital TV as described above, or the like. A system, in which the printer, directly connected to the AV device, prints the image data based on print content description data that is generated by such application, has been conceived. However, under a non-PC printing system in which an AV device other than a digital camera and a PC (hereinafter to be referred to as a “host device”) serves as a host, a host device does not have a sufficient resource such as a memory for generating print data as the PC does, and also, operating systems (OS) of the host devices differ from one another, depending on a company. It is therefore difficult to install, into the host device, plural printer drivers corresponding to each printer.
Consequently, under the non-PC printing system, the host device which instructs on printing generates only print content description data using a description language that the printer can analyze, but does not generate print data as in the case of using a normal printer driver installed in the PC. It is the printer that analyzes the print content description data and generates print data. That is to say, the host device generates the print content description data in a text format as shown in FIGS. 2 and 3A, while the printer generates the print data of bit image as shown in FIGS. 1 and 4 based on the print content description data. Under the non-PC printing system as described above, the printer detects a location (file pass) of the image data (e.g., FIGS. 3B and 3C) necessary for printing and obtains the image data actively. It should be noted that FIGS. 2 and 3A show examples of the print content description data while FIGS. 3B and 3C show examples of the image data. FIGS. 1 and 4 show examples of the print data of bit image. The print content description data here means the data described by the print content description language.
Under the direct-printing system, in which the printer prints the image data directly transmitted from the digital camera, the printer uses only the image data of thumbnail images in the Exif file, which is obtained from the digital camera in the case of creating an index print, as already mentioned above. Thus, the printer uses the image data of thumbnail images, not the image data of main images. Therefore, the time required to complete the printing of the index print using the image data of thumbnail images is shorter, compared to the case of the printing with the use of the image data of main images.
On the other hand, under the non-PC printing system, it is the application installed in the host device that generates the print content description data, as mentioned above. In the case of creating an index print, it is the application that generates the print content description data for index print, using the description language which can be analyzed by the printer. That is to say, the application generates the print content description data which indicates that the plural images are arranged in an array to be printed. The host device then transmits, to the printer, the print content description data for index print.
The printer, having received such print content description data, however, processes in the same manner as required for a normal photo printing, unless that the print content description data is for index print is explicitly indicated. Namely, the printer does not obtain the image data of thumbnail images included in the Exif file, but the image data of main images from the host device. The printer, with a function to process high-quality image, also performs the high quality image processing on image data, as in the normal case. Thus, the printer, if equipped with such function, obtains the image data of main images which requires a huge data amount, and performs the high-quality image processing on the obtained image data. Therefore, it requires a huge amount of time in order to complete the printing of the index print.
The general aim of creating an index print, in many cases, is to obtain a list of plural images in order to see the images or to get the names of the files. That is to say, the high-quality image printing as required for a normal photo printing is not required so much in such cases. It is therefore possible to reduce the time required for printing the print content description data for index print generated by the application in the host device, provided that printing the index print, which is different from the normal photo printing, is operated.
For this, all that is needed is to indicate explicitly that the print content description data transmitted from the host device is for printing an index print. In order to realize this, it is conceivable that the host device sends to the printer a command indicating that the print content description data for index print has been transmitted. In this case, however, it is required that both the host device and the printer understand such command. This can be realized when the host device and the printer are the products of the same maker since a command can be uniquely defined by each maker. In the case in which the host device and the printer are the products of different makers, a command needs to be standardized. As far as the command is not standardized, the printer obtains the image data of main images having a huge data amount for all the images to be listed up in the index print, and generates the print data, unless it is explicitly indicated that the print content description data is for index print. This requires a great amount of time for printing the index print.
Under the non-PC printing system, the printer obtains the image data of main images having a huge amount of data regardless of the number of pixels in the image at the time of printing, and generates the print data for printing the images other than those for index print. When an image is printed at the number of pixels that is smaller than a predetermined number of pixels, for example, in a case of printing image data of 1600×1200 pixels as a bit image of 160×120 pixels, or in the similar cases, a great part of the pixels in the original image data are cut off. Also, printing images with high quality is not specially required since the printing area is small. This is because, for the above case, human beings cannot judge whether the printed image is of high or low quality. In this case, where the printing images with high quality is not required, the printer obtains the image data of main images requiring a huge amount of data and generates the print data, in spite that the print data can be generated from the image data of thumbnail images. Consequently, it requires a great amount of time for printing the data.
As is mentioned above, under the non-PC printing system, the printer obtains the image data of main images requiring a huge amount of data and generates the print data, without explicit instructions, even when printing with high quality is not required as in the case of printing an index print or in the case of printing the image whose number of pixels is smaller than a predetermined number of pixels. As a result, it requires a great amount of time for printing the data.